1. Field of Invention
The present invention relates to an image display method, an image display device, and electronic equipment in which a reduction in the display quality can be reduced or prevented when data is read from a display memory to display an image.
2. Description of Related Art
Typically, bitmap display panels, such as organic EL (Electroluminescent) devices and liquid crystal devices, use a method in which reading addresses from a display memory are sequentially designated (read and scanned) in synchronization with vertical and horizontal scanning in order to form a display according to the read grayscale data. The addresses of the display memory (also sometimes called a “frame memory” or a “video memory”) have a one-to-one correspondence with the pixels constituting the display device. Each of the addresses stores grayscale data to specify the gray level (density or intensity) of the corresponding pixel. Thus, each time a host control circuit, such as a CPU, refreshes the content stored in the display memory, the image displayed on the display panel is also updated accordingly.
If the host control circuit refreshes the content stored in the display memory during the reading and scanning operation, then, for one vertical scanning period (one frame) in which the content was refreshed, a mixture of the display based on the stored content that has not been refreshed and the display based on the stored content that has been refreshed is shown (tearing), thus possibly causing the display quality to be significantly reduced.
In order to reduce or prevent a reduction in the display quality, therefore, it is necessary that the host control circuit perform a procedure synchronous with the reading and scanning operation, such that an instruction to refresh the grayscale data during a period other than the reading and scanning period is given.